seems like weak betting......betting half the pot when the flush comes signifies to me an informational bet, maybe with a pair or something that may get pushed out by the flush....Guy may come over hoping for the one card flush to his high card....He may have had 2 pair or TPTK....

When you simply called his reraise, he may have seen you on a one card flush draw, looking to get odds on the hand....

I think the $2 bet was weak....that gave him signals you were weak when in fact you were strong....